Tag Archives: Noise

“I am thinking of the new RSP1A SDR. Would you know of a good indoor antenna that would work well with it?”

Your antenna question is simple, but the answer is complex!

First off, I think the RSP1A is a great choice as it’ll give you proper exposure to the world of SDR (1 kHz to 2 GHz!) at a modest price.

Unlike a portable radio of course, your SDR must be connected to a PC, laptop, tablet or some sort of mini computer like Raspberry Pi. This limits your ability to easily try different antenna locations within your home compared to, say, a battery-powered portable radio. It might take some dedicated experimentation and patience.

Indoor antennas are so vulnerable to the radio noise within your home.

If you live in an off-grid cabin with no radio interference nearby, even a simple $1 random wire antenna hooked up to RSP1A’s SMA connector would yield results. I occasionally spend my summers in an off-grid cabin and it’s simply amazing what you can do with a modest setup when there are no man-made radio noises around.

Listening to the final broadcast of Radio Netherlands in an off-grid cabin on Prince Edward Island in 2012.

But how many radio enthusiasts live in an off-grid cabin? Answer: very, very few! Most of us only get to experience off-grid life during natural disasters when the electrical grid has been damaged in our neighborhoods.

The reality of indoor antennas

You’ve told me previously that you live in an apartment in an urban setting, hence you probably cope with a lot of RFI.

When an antenna is indoors, it is forced to function within this RFI-dense environment. Your telescoping whip or wire antenna doesn’t discern between radio noise and your target broadcast signal. Thus, noise can overwhelm your receiver, essentially deafening it to all but the strongest shortwave broadcasters.

This is why if you had a means to put a small random wire antenna outside–even if it was simply draped outside a window–it would likely perform better than an indoor antenna. I’m guessing this isn’t an option for you, Chris.

While you can build an amplified mag loop antenna (like our buddy, TomL) it’s not a simple project. Passive single turn loop antennas, on the other hand, are quite easy to build but are narrow in bandwidth (here’s a very cheap, simple passive loop project). You would likely design a single passive loop to serve you on a specific brodcast band and would have to retune it as you make frequency changes. You could build a passive loop antenna for less than ten dollars if you can find a good variable capacitor. Here’s another tutorial.

Commercially produced amplified wideband magnetic loop antennas are not cheap, but they are effective. If you’re a serious SWL, a good mag loop antenna is worth the investment.

W6LVP Loops

W6LVP sells two versions of the antenna–since you’re not operating a transmitter, this $250 model would be all you need. indeed, if I were in your shoes, this would likely be the loop I purchase–very cost effective.

Wellbrook Loops

Wellbrook antennas are the staple magnetic loop antenna for many DXers.

Wellbrook makes a number of loops, but since you have no plans to mount this outside, I believe their indoor model would suffice.

Other loop options

There’s no shortage of magnetic loop antennas on the market, but most are pricer than the models I mention above and I know you have a tight budget. Here’s are some models we’ve mentioned on the SWLing Post in the past:

I hope this helps, Chris! This post is by no means comprehensive, so I hope others will chime in and comment with their experiences. Good luck fighting urban noise and I hope you enjoy your journey into the world of the SDR!

I am experiencing a issue with my shortwave reception at my part-time home. I have been helping out my mother so I have brought over my Sony portable, along with the Sony active antenna. I have a constant ‘clicking’ sound starting at about 5 kHz or thereabouts that make listening unbearable. As the video shows the problem is non-existent below 4 kHz. I tried moving the radio throughout the house thinking it could be something in the room and still get the same interference.

I was hoping that the filter on the active antenna would help but it does little to remedy the problem. I have no issues with MW or FM reception at all.

I have made a short YouTube video to document the problem in the hopes that one of the blog readers can identify it. I looked online at other instances of RFI and I could not find one that is similar. Hope that someone can help me!

After listening to the first few seconds of your recording, I thought it sounded a bit like an electric fence controller. However the interval between pops is nearly random, which suggests a different source. I suppose it’s possible a faulty fence controller could do this. I believe the only way you could defeat this noise (without shutting it down at the source) would be to use a radio with a durable noise blanker. Of course, I know of no portable radios with an NB function (though most SDRs and tabletop receivers include an NB).

Post readers: Can help Luke ID the source of this noise? Does it sound familiar to you? Please comment!

A federal agent who shows up unannounced at a building along a Texas highway might be looking for any number of things: illicit drugs or immigration violations, say, or illegal firearms.

Or fluorescent lights.

Which was what the agent had in mind who walked into the Perfect Cuts salon in San Antonio last July. The lights were violating communications regulations.

The agent had used signal-tracking equipment to home in on the offenders and told the owner, Ronald Bethany, that his lights emitted radio signals that interfered with an AT&T cellphone tower.

[…]The mixed signals aren’t always so weighty. In recent years, the FCC has issued warning letters directing people to stop operating cordless phones, television sets and wireless cameras.

[…]The FCC can demand fines up to $16,000 a day or $112,500 an incident from people who aren’t FCC licensees. Offenders usually rectify problems, the FCC says, often working them out with whomever is complaining.

Managing the radio spectrum “has been part of our core mission since the inception of the FCC in 1934,” says Julius Knapp, head of the agency’s Office of Engineering and Technology.

[…]The government doesn’t much care why interference happens. To the FCC, noise is noise.

In a 2013 letter, the FCC wrote to the owner of a plasma TV set after a ham-radio operator complained to the agency of interference. “Continued operation of the television,” warned the letter, from which the TV owner’s identification is redacted, “is not legal under FCC rules.”

[…]Ham-radio operators are a frequent source of complaints. A 2012 FCC letter told a Pomona Park, Fla., resident to stop using a well pump that conflicted with amateur-radio frequencies.

[…]Radio hobbyist Tom Thompson of Boulder, Colo., last year tracked a signal using a homemade contraption. After knocking on the suspect’s door, he traced it to ballasts on marijuana grow-room lights. He says he built a filter that the grower agreed to use.

Ballasts are frequent offenders. Makers of the components, which regulate electricity to bulbs, test them for FCC compliance. Some interfere anyway.[…]

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